Comparison of the Index System of Ecological Balanced Fertilization for Three Crops

This paper conducted comparative study of the index system of ecological balanced fertilization for rice,wheat and maize by data mining method based on data of"3414 fertilizer field trials"of rice,wheat and maize by published papers from national soil testing and recommendation since 2005.The main conclusions of this paper were as follow:①since the three crops all belonged to Gramineae,they were consistent in variation trends of fertilizer utilization ratio,nutrient conversion rate,relative abundance-deficiency value of soil nutrient,optimum fertilization amount in most cases.②Due to the influence of the economic production,biological production,different water conditions in paddy field and dry farmland,length of growing season,cropping system(one year before and after the rotation)and so on,sometimes the laws of four aspects above mentioned for the three crops had opposite and gradient variations.

Studies on the Provincial-level Index System of Ecological Balanced Fertilization for Rice in China

In this paper,the index system of ecological balanced fertilization for rice was discussed by data mining method based on this column.Three aspects of provincial average,typical province and all samples were studied,and the results and conclusions were as follows:①climate condition was one of the main factors of soil formation,which was also an important basis for the division of rice growing areas.The proportion of available nutrients was different in different rice growing areas.This was the result of long-term climate and man-made action,which constituted the basic fertility pattern of soil available nutrients for rice in China.②One of the basic fertility indexes of rice soil in China was the proportion of available nutrients,which was the theoretical basis for adjusting the proportion of N,P and K fertilizers.③Although the total amount and proportion of available nutrients in different rice growing areas were different,they can be adjusted to the optimum absorption ratio of rice by fertilizing measures,so as to achieve the goal of ecological balanced fertilization such as high production and good quality.④The basic soil nutrient index of more than 8000 kg/hm 2 of rice production was more than 5 of available K/available P.

Theoretical Analysis on Index System of Ecological Balanced Fertilization for Three Crops

This paper analyzed theoretical basis of ecological balanced fertilization by data mining method based on the relationships among relative abundance-deficiency values of soil nutrients,optimum fertilization amounts and nutrient conversion rates of N,P and K for rice,wheat and maize in column papers.The results and conclusions were as follows:①the scientific basis of guiding fertilization by the relative abundance-deficiency value of soil nutrient was insufficient.②The scientific basis for predicting fertilizer amount according to nutrient conversion rate was sufficient.③There was consistency among the relative abundance-deficiency values of soil nutrients,indicating that the soil nutrient balance was important to the production.④There was some consistency among the optimum fertilizer amounts,indicating that N,P and K fertilizer should be balanced.⑤There was some consistency among nutrient conversion rates,indicating that nutrient uptake was consistent,which required the consistency among relative abundance-deficiency values of soil nutrients.When there was inconsistency,it needed to be supplemented by means of fertilization.⑥The relative abundance-deficiency value of soil nutrient and optimum fertilizer amounts of other nutrients were negatively correlated mostly,indicating that if the relative abundance-deficiency value of soil nutrient was high,the others also should be high,resulting in optimum fertilizer amounts of other nutrients decreased.⑦The nutrient conversion rate was negatively correlated mostly with the optimal fertilizer amounts of other nutrients,indicating that more fertilizer amount of one nutrient lowered its own conversion rate,mean while also reduced the conversion rates of other nutrients.It embodied the unity and balance of nutrient absorption by the crops.

Specific Index System of Ecological Balanced Fertilization for Maize

This paper studied the index system of ecological balanced fertilization for maize by data mining method based on data of"3414 fertilizer field trials"of maize by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows.①Soil nutrient content could not be used as indicator of fertilizer application of maize.②The conceptual model of N conversion rate of maize for plot was Y N≈a+b×optimum production-c×optimum fertilizer amount of N-d×optimum phosphorus application amount-e×optimum potassium application amount-f×temperature in growth season-g×rainfall in growth season.The conceptual model of P conversion rate of maize for plot was Y P≈a+b×optimum phosphorus application amount-c×optimum nitrogen application amount-d×optimum potassium application amount.The conceptual model of K conversion rate of maize for plot was Y K≈a+b×optimum yield-c×optimum nitrogen application amount-d×optimum phosphorus application amount-e×optimum potassium application amount-f×temperature in growth season-g×rainfall in growth season.③The conceptual model of the optimum fertilizer amount of N of maize for plot was Y N≈a+b×optimum phosphorus application amount+c×optimum potassium application amount+d×temperature in growing season+e×rainfall in growing season,and the conceptual model of the optimum fertilizer amount of P was Y P≈a+b×optimum nitrogen application amount,and the conceptual model of the optimum fertilizer amount of K was Y K≈a+b×optimum nitrogen application amount+c×temperature in growth season+d×rainfall in growth season-e×optimum yield.④The conceptual model of relative abundance-deficiency value of soil N of maize for plot was that Y N≈a,and the conceptual model of relative abundance-deficiency value of soil P was Y P≈a,and the conceptual model of relative abundance-deficiency value of soil K was Y K≈a+b×optimum nitrogen application amount+c×optimum phosphorus application amount.

Summary on the Index System of Ecological Balanced Fertilization for Maize

This paper studied the index system of ecological balanced fertilization for maize by data mining method based on data of"3414 fertilizer field trials"of maize by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the optimum N,P and K fertilization amounts of maize were within the normal range,and the application of this standard could not cause obvious non-point source pollution.②The conversion rates of N,P and K of maize were respectively higher than their respective utilization ratios under the optimum fertilization amount.③At present,the soil N for maize was in an absence state,and soil P and K were in a state of not obvious lack.④Optimum N,P and K fertilization amounts were significantly negatively correlated with their respective conversion ratios,respectively,and it provided a quantitative scientific basis for calculating the optimum fertilization amount according to the nutrient conversion rate.Each province can use this significant relationship to guide the determination of the average optimal fertilization amounts of N,P and K and the optimal production in the province.⑤The research results of nutrient conversion rate showed that any excessive application of N,P and K would reduce their own nutrient conversion rates,and may also reduce the conversion rates of other nutrients.The characteristics of crops absorbing N,P and K proportionally required that soil nutrients must be balanced in order to obtain high production,and fertilization was only the main means to regulate soil nutrient balance.

Summary on the Index System of Ecological Balanced Fertilization for Rice

This paper studied the index system of ecological balanced fertilization for rice by data mining method based on data of"3414 fertilizer field trials"of rice by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the optimum N,P and K fertilization amounts of rice were within the normal range,and the application of this standard could not cause obvious non-point source pollution.②N,P and K conversion ratios were 76.4%,166.58%and 261.89%higher than N,P and K utilization ratios under the optimum fertilizer amount of rice,respectively.③At present,the soil N for rice was in a low equilibrium stage,and soil P and K were in the middle and high level,in which P was in the accumulation stage,while K was in the depletion stage.④The relationship between fertilizer effect or fertility and optimum production had consistency.The fertilizer effect was negatively correlated with the optimum fertilization amount of its own nutrient.N,P and K fertilizers had mutual promoting effect when they were balanced.Soil nutrient played an inhibitory role in the fertilizer efficiency of its own nutrient.Soil nutrient sometimes played a role in promoting the efficiency of other nutrients,and sometimes inhibited them.It was a positive correlation between soil nutrients with the same attribute.

Specific Index System of Ecological Balanced Fertilization for Rice

This paper studied the nitrogen index system of ecological balanced fertilization for rice by data mining method based on data of"3414 fertilizer field trials"of rice by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows.①Soil nutrient content could not be used as fertilization indicator of rice.②The conceptual model of nitrogen conversion rate of rice for plot was Y N≈a+b×optimum production-c×optimum nitrogen fertilization amount-d×optimum phosphorus fertilization amount,and the conceptual model of phosphorus conversion rate was Y P≈a-b×optimum phosphorus fertilization amount-c×optimum potassium fertilization amount,and the conceptual model of potassium conversion rate was Y K≈a+b×optimum production+c×optimum nitrogen fertilization amount-d×optimum potassium fertilization amount-e×annual average precipitation.③The conceptual model of the optimum nitrogen fertilization amount of rice for plot was Y N≈a+b×optimum production+c×optimum phosphorus fertilization amount-d×annual average precipitation,and the conceptual model of the optimum phosphorus fertilization amount was Y P≈a+b×optimum nitrogen fertilization amount+c×optimum potassium fertilization amount,and the conceptual model of the optimum potassium fertilization amount was Y K≈a+b×optimum phosphorus fertilization amount+c×annual average precipitation.④The conceptual model of relative abundance-deficiency value of soil nitrogen of rice for plot was Y N≈a-b×optimum nitrogen fertilization amount-c×optimum potassium fertilization amount,and the conceptual model of relative abundance-deficiency value of soil phosphorus was Y P≈a+b×soil available potassium-c×optimum potassium fertilization amount,and the conceptual model of relative abundance-deficiency value of soil potassium of rice was Y K≈a-b×optimum potassium fertilization amount.

Studies on the Provincial-level Index System of Ecological Balanced Fertilization for Maize in China

In this paper,the index system of ecological balanced fertilization of maize was discussed by data mining method based on this column.Three aspects of provincial average,typical province and all samples were studied,and the results and conclusions were as follows:①climate condition was one of the main factors of soil formation,which was also an important basis for the division of maize producing areas.The proportion of available nutrients was different in different maize producing areas.This was the result of long-term climate and man-made action,which constituted the basic fertility pattern of soil available nutrient for maize in China.②One of the basic fertility indexes of maize soil in China was the proportion of available nutrients,which was the theoretical basis for adjusting the proportion of N,P and K fertilizers.③Although the total amount and proportion of available nutrients in different maize producing areas were different,they can be adjusted to the optimum absorption ratio of maize by fertilizing measures,so as to achieve the goal of ecological balanced fertilization such as high production and good quality.④The basic soil nutrient index of more than 9000 kg/hm 2 of maize production was less than 8 of hydrolysable N/available P,and the fertilization index was that optimum N fertilization amount was more than 0.8 times of optimum P fertilization amount.

Studies on the Provincial-level Index System of Ecological Balanced Fertilization for Wheat in China

In this paper,the index system of ecological balanced fertilization for wheat was discussed by data mining method based on this column.Three aspects of provincial average,typical province and all samples were studied,the results and conclusions were as follows:①climate condition was one of the main factors of soil formation,which was also an important basis for the division of wheat producing areas.The proportion of available nutrients was different in different wheat producing areas.This was the result of long-term climate and man-made action,and it constituted the basic fertility pattern of soil available nutrient for wheat in China.②One of the basic fertility indexes of soil for wheat in China was the proportion of available nutrients,which was the theoretical basis for adjusting the proportion of N,P and K fertilizers.③Although the total amount and proportion of available nutrients in different wheat producing areas were different,they can be adjusted to the optimum absorption ratio of wheat by fertilizing measures,so as to achieve the goal of ecological balanced fertilization such as high production and good quality.④The basic soil nutrient indexes of more than 5000 kg/hm 2 of wheat production were less than 6 of hydrolysable N/available P and less than 7 of available K/available P,and the fertilization index was that optimum K fertilization amount was 0.6-1.2 times of optimum P fertilization amount.

Specific Index System of Ecological Balanced Fertilization for Wheat

This paper studied the index system of ecological balanced fertilization for wheat by data mining method based on data of"3414 fertilizer field trials"of wheat by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows.①Soil nutrient content could not be used as indicator of fertilizer application of wheat.②The conceptual model of N utilization ratio of wheat for plot was Y N≈a+b×optimum production-c×optimum fertilizer amount of N-d×temperature in growing season-e×rainfall in growing season,and the conceptual model of P conversion rate was Y P≈a+b×optimum production+c×temperature in growing season+d×precipitation in growing season-e×optimum fertilizer amount of P-f×optimum fertilizer amount of K,and the conceptual model of K conversion rate of wheat plots was that,Y K≈a-b×optimum fertilizer amount of K.③The conceptual model of the optimum fertilizer amount of N of wheat for plot was Y N≈a+b×optimum production+c×optimum fertilizer amount of P-d×temperature in growing season-e×rainfall in growing season,and the conceptual model of the optimum fertilizer amount of P was Y P≈a+b×optimum production+c×optimum fertilizer amount of N+d×optimum fertilizer amount of K,and the conceptual model of the optimum fertilizer amount of K was Y K≈a+b×optimum fertilizer amount of P.④The conceptual model of relative abundance-deficiency value of soil N of wheat for plot was that Y N≈a-b×temperature in growing season-c×precipitation in growing season,and the conceptual model of relative abundance-deficiency value of soil P was Y P≈a+b×optimum yield+c×optimum fertilizer amount of N+d×precipitation in growing season-e×optimum fertilizer amount of K,and the conceptual model of relative abundance-deficiency value of soil K was Y K≈a+b×optimum yield+c×optimum fertilizer amount of K.

Research on the Index System of Ecological Balanced Fertilization for Three Crops

This paper studied the index system of ecological balanced fertilization for three crops by data mining method based on data of"3414 fertilizer field trials"of rice,wheat and maize by published papers from national soil testing and recommendation since 2005.A systematic analysis of the materials and methods,the main research contents,the main research results and the main research conclusions of the column was made,in order to enable readers to understand and grasp the overall contents of the following 15 papers.

Summary on the Index System of Ecological Balanced Fertilization for Wheat

This paper studied the index system of ecological balanced fertilization for wheat by data mining method based on data of"3414 fertilizer field trials"of wheat by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the optimum N,P and K fertilization amounts of wheat were within the normal range,and the application of this standard could not cause obvious non-point source pollution.②The conversion rates of N,P and K of wheat were 58.78%,58.63%and 199.88%higher than the utilization ratios of N,P and K under the optimum fertilization amount,respectively.③At present,the soil N for wheat was in a low equilibrium stage,and soil P and K were in the middle and high levels,in which P was in the accumulation stage,and K was in the depletion stage.④The relationship between fertilizer effect or fertility and optimum production had consistency.The fertilizer effect was negatively correlated with the optimum fertilization amounts of its own nutrient and other nutrients.N,P and K fertilizers had mutual promoting effects when they were balanced.Soil nutrient played an inhibitory role in the fertilizer efficiency of its own nutrient.⑤The phosphorus and potassium utilization ratios were significantly positively correlated with the optimum phosphorus fertilization amount and the optimal potassium fertilization amount,which was the scientific basis for phosphorus and potassium concentrated fertilization of wheat.

Research and Application of Prediction Model for Ecological Balanced Optimal Fertilization Amount for Three Crops

This paper analyzed the modeling principle,process and application process of the new ecological balanced fertilization model by data mining method based on the relationships among soil abundance-deficiency index,optimum fertilization amount and nutrient conversion rate of N,P,K for rice,wheat and maize in column papers.The results and conclusions were as follows:①on the basis of two ecological balanced fertilization models(available and total nutrients),a prediction model system of optimum fertilization amount based on nutrient conversion rate was established,including 3 models.The first model predicted the optimum fertilization amount based on nutrient conversion rate,and the second model determined prediction difference value of optimum fertilization amount in the first amendment based on optimum yield,and the third model determined prediction difference value of optimum fertilization amount in the second amendment based on nutrient conversion rate.②Nutrient conversion rate and optimum yield were the common parameters of two models based on contents of available and total nutrients,and they were the core parameters of ecological balanced fertilization model.In the specific application,the nutrient conversion rate and optimum yield were determined mainly based on the comprehensive comparison between the regional or similar plot or one plot and the experimental plot.③The two error amendments were due to the use of the fixed nutrient removal of 100 kg seeds,and underestimated the nutrient conversion rate when higher optimum production and overestimated the nutrient conversion rate when lower optimum production.④It was proposed that the nutrient conversion rate was regarded as a comprehensive nutrient index(abundance-deficiency)of ecological balanced fertilization.It was not only a parameter to measure fertilizer efficiency,but also a parameter to measure the abundance-deficiency of nutrients,and a parameter to guide fertilization.

Research on the Production Efficiency and Utilizing Rate of Potassium Fertilizer for Rape in Yunnan Province

[Objective] This study aimed at investigating the effects of consumption of potassium fertilizer on production and biological characteristics of rape and utilizing efficiency of potassium fertilizer.[Method] Taking 0 kg/hm2 as control,nine consumptions of potassium fertilizer were designed for the experiment using single factor randomized block design with three replications and field experiment in nine rape-producing areas with different ecological types in Yunnan Province.[Result] Appropriately applying potassium fertilizer in Yunnan Province could improve the rapeseed production,the rape production could achieve 3 983-4 151 kg when applied 150-180 kg/hm2 of K2O,which had increased by 4.7-9.1% compared with the control and attained the peak in K165 treatment.When applied 1 kg of K2O,the rapeseed production could enhance 559 kg,the net profit could reach 1 229 yuan/hm2 and the partial productivity of potassium fertilizer could attain 31.32 kg/kg K2O and 3.7 kg/kg K2O,respectively.Applying potassium fertilizer could promote the growth of rape and increase rapeseed production.[Conclusion] The recommended optimal consumptions of potassium fertilizer with high production and high efficiency for rape in Yunnan Province were ranged between 150 and 180 kg K2O/hm2.However,comprehensively considering production and efficiency factors,the consumption of potassium fertilizer in Yunnan Province was around 73.9 kg/hm2,which should be appropriately increased to around 100.0 kg/hm2 in Longchuan,Yulong,Linxiang and other producing areas with similar conditions.

Effects of Increased Planting Density with ReducedNitrogen Application on Yield Formation and NitrogenUtilization of Autumn Maize

With the change of cropping system in the middle reaches of the Yangtze River,the planting area of autumn maize is gradually increasing.However,the cultivation techniques are still under improvement for higher yield and nitrogen efficiency of autumn maize.Increase in planting density with reduced nitrogen fertilizer application is one of the important paths to achieve high yield and high nitrogen utilization efficiency.Meanwhile,the effect needs to be verified for autumn maize.The semi-compact autumn maize variety Qinyu 58 was planted under different planting densities and nitrogen fertilizer amounts with the split plot design.Different nitrogen application rates were arranged in the main plots,including the conventional nitrogen application(N300,300 kg/hm^2),30%reduction from the conventional treatment(N210,210 kg/hm^2)and no nitrogen application(N0).Different planting densities were arranged in the sub-split plots,including the conventional planting density(D60,60000 plants/hm2),medium density(D78,78000 plants/hm^2)and high density(D93,93000 plants/hm2).The effects of nitrogen fertilizer,planting density and their interaction effects on canopy structure,dry matter accumulation,yield and nitrogen use efficiency of autumn maize were studied.The nitrogen application rate and planting density had obvious interaction effects on the yield formation of autumn maize.Compared with the conventional cultivation(N300D60),increasing the planting density with 30%reduction in nitrogen application(N210)can obviously increase the canopy light interception rate,LAI,dry matter accumulation and yield.However,there was no significant change in canopy light interception rate,LAI,dry matter accumulation,grain weight and yield between D93 and D78.Compared with N300D60,nitrogen translocation efficiency and nitrogen contribution proportion to grain nitrogen did not change significantly in autumn maize grown under N210 and D78 treatments,whereas nitrogen partial productivity,nitrogen agronomic efficiency and recovery and utilization efficiency of nitrogen fertilizer increased significantly.Moreover,high density(D93)planting at N210 plots significantly improved nitrogen transport efficiency and utilization efficiency in autumn maize.Therefore,the suitable planting density of the autumn maize variety Qinyu 58 in Hubei Province is recommended a value of 78000 plants/hm^2,with the nitrogen application rate of 210 kg/hm2,which can achieve the target of higher yield by increasing density and reducing nitrogen.

Advances in Studies of Biological Nitrogen Saving Technology for Wheat

This paper first described the current status of wheat nitrogen fertilizers utilization rate. Then,from balanced fertilizer application,applying slow/controlled release fertilizer,deep application of nitrogen fertilizers and graded application,controlled application amount,selection of application time according to soil properties,diagnosed application of fertilizer with instrument,addition of synergist,and precise fertilizer application,it summarized biological nitrogen saving methods and introduced prospects of future biological nitrogen saving technology.

Study on the Relationships between Utilization Ratios and Conversion Rates of Nitrogen,Phosphorus and Potassium for Wheat

This paper studied the relationships between utilization ratios and conversion rates of nitrogen,phosphorus and potassium for wheat by data mining method based on data of"3414 fertilizer field trials"of wheat by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the conceptual model of fertilizer utilization ratio of wheat for plot was that,Y N≈a+b×optimum nitrogen application amount+c×optimum fertilizer amount of K+d×rainfall in growth season,Y P≈a+b×optimum fertilizer amount of K+c×rainfall in growth season,Y K≈a+b×temperature in growth season+c×rainfall in growth season-d×optimum yield-e×optimum nitrogen application amount,respectively.②Fertilizer utilization ratio and nutrient conversion rate had 4 kinds of relationships.No significant relationships:13,of which 8 were soil nutrients,the results showed that soil nutrients had little effect on nutrient conversion rate and fertilizer utilization ratio;consistent significant relationships:4,they were all nitrogen and phosphorus,explaining the importance of nitrogen and phosphorus;contrary significant relationships:6,they were all nitrogen and phosphorus,illustrating that phosphorus and nitrogen had inhibitory effect;complementary significant relationships:31,the cause of the complementary phenomenon was that the fertilizer utilization ratio was the measuring index of fertilizer efficiency in one season,while the nutrient conversion rate was the measuring index of fertilizer efficiency in more seasons.It showed that the fertilizer utilization rate was significantly correlated,or the nutrient conversion rate was significantly correlated.

Study on the Relationships between Utilization Ratios and Conversion Rates of Nitrogen,Phosphorus and Potassium for Maize

This paper studied the relationships between utilization ratios and conversion rates of nitrogen,phosphorus and potassium for maize by data mining method based on data of"3414 fertilizer field trials"of maize by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the conceptual model of fertilizer utilization ratio of maize for plot was that,Y N≈a+b×optimum yield,Y P≈a+b×optimum yield-c×optimum nitrogen application amount-d×optimum potassium application amount,Y K≈a-b×optimum nitrogen application amount-c×temperature in growth season-d×rainfall in growth season,respectively.②Fertilizer utilization ratio and nutrient conversion rate had 4 kinds of relationships.No significant relationships:22,of which 16 were soil nutrients and 5 were environmental factors,the results showed that soil nutrients and environmental factors had little effect on nutrient conversion rate and fertilizer utilization ratio;consistent significant relationships:14,illustrating that conversion rate and utilization ratio of maize were consistent in most cases,and it was because that maize was planted for a long term,and its fertilizer absorption law was basically stable;contrary significant relationships:0,illustrating that there was no reverse relationship between conversion rate and utilization ratio of maize;complementary significant relationships:18,the cause of the complementary phenomenon was that the fertilizer utilization ratio was the measuring index of fertilizer efficiency in one season,while the nutrient conversion rate was the measuring index of fertilizer efficiency in more seasons.It showed that the fertilizer utilization ratio was significantly correlated,or the nutrient conversion rate was significantly correlated.

Study on the Relationship between Utilization Ratios and Conversion Rates of Nitrogen,Phosphorus and Potassium for Rice

This paper studied the relationships between utilization ratios and conversion rates of nitrogen,phosphorus and potassium for rice by data mining method based on data of"3414 fertilizer field trials"of rice by published papers from national soil testing and recommendation since 2005.The results and conclusions were as follows:①the conceptual model of fertilizer utilization ratio of rice for plot was that,Y N≈a+b×optimum yield+c×optimum fertilizer amount of K,Y P≈a+b×optimum yield,Y K≈a respectively.②Fertilizer utilization ratio and nutrient conversion rate had 4 kinds of relationships:①no significant relationships:25,of which 14 were soil nutrients and 9 were environmental factors,the results showed that soil nutrients and environmental factors had little effect on nutrient yield ratio and fertilizer utilization ratio;②consistent significant relationships:2,one was that yield ratio and utilization ratio of N were positively correlated with the optimum production,explaining the importance of N for production,the other was that yield ratio and utilization ratio of P had a significantly positive correlation with conversion rate and utilization ratio of N,illustrating that nitrogen and phosphorus had mutual promotion;③contrary significant relationships:5,these showed as negative correlations of fertilizer utilization ratio and positive correlation of nutrient conversion ratio;④complementary significant relationships:22,the cause of the complementary phenomenon was that the fertilizer utilization ratio was the index of fertilizer efficiency in one season,while the nutrient conversion rate was the index of fertilizer efficiency in more seasons,which showed that the fertilizer utilization rate was significantly correlated,or the nutrient conversion rate was significantly correlated.

Effect of nitrogen fertilizer on the uptake and utilization of potassium by various rice varieties in purple soil

Nitrogen and potassium are important nutrientelements for rice.Besides supplied by the or- ganic manure,potassium nutrition of ricecomes dominantly from purple soils in Sichuanbasin.Potassium exists abundantly in mineralforms in the purple soils.Availability of soilpotassium for crop depends on the potassiumforms,the uptake ability of crops,and fertiliz-er practices.A pot culture experiment wasconducted to study the kinetics of potassiumuptake in the purple soil(total N 22.64g·kg,total K 24.36g·kg,available N 102.6mg·kg,available K 140.6mg·kg,acidsoluble K 936.0mg·kg,and pH 6.8).Ma-terials used were three Fhybrid rices,Eryou